If $3a + 3b = -2$ and $7x + 9y + 5z = 1$, what is $6b + 36y + 28x + 6a + 20z$ ?
Explanation: $= 6a + 6b + 28x + 36y + 20z$ $= (2) \cdot (3a + 3b) + (4) \cdot (7x + 9y + 5z)$ $= (2) \cdot (-2) + (4) \cdot (1)$ $= -4 + 4$ $= 0$